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Cited by 151Cardiovascular Syncope and Autonomic DisordersCardiac pacing and defibrillation studiesHeart Rate Variability and Autonomic Control

The expectation effect and cardiac pacing for refractory vasovagal syncope

Sud, Sachin, Massel, David, Klein, George J., Leong-Sit, Peter, Yee, Raymond, Skanes, Allan C., Gula, Lorne J., Krahn, Andrew D.·2007·The American Journal of Medicine
DOI 10.1016/j.amjmed.2006.05.046
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Abstract

Background Clinical trials of pacing for vasovagal syncope have shown conflicting results. We performed a meta-analysis to determine whether permanent pacemaker therapy prevents refractory vasovagal syncope.Methods Randomized trials comparing pacemaker therapy with medical therapy, usual care, placebo, or different pacing algorithms in the prevention of recurrent vasovagal syncope were considered. The primary endpoint was first recurrence of syncope.Results Nine randomized trials (2 double blind, 7 open label or single blind) were included. There was significant heterogeneity when all 9 trials were pooled (P=.0009 and I(2)=69.6%), reflecting methodological diversity in blinding and the nature of the control therapy. When pooled by trial methodology, heterogeneity was no longer apparent. Permanent pacing reduced the risk of recurrent syncope in unblinded studies (odds ratio [OR] 0.09, 95% confidence interval [CI], 0.04 to 0.22) and in studies comparing pacemaker algorithms (OR 0.04, 95% CI, 0.0 to 0.23). No effect was seen in double-blinded trials (OR 0.83, 95% CI, 0.41 to 1.70). Awareness that a permanent pacemaker was implanted and functional was associated with a significant 'expectation' effect, which itself reduced the risk of recurrent syncope (OR 0.16, 95% CI, 0.06 to 0.40, P=.0001). Results were similar when restricted to patients with a marked cardioinhibitory response on baseline tilt table testing.Conclusion The results of small, preliminary trials have overestimated the treatment effect of pacemakers due to a lack of blinding of physicians and patients. Blinded trials suggest that the apparent response is due to a strong expectation response to pacing.

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  • A meta-analysis of all studies suggested a non-significant 17% reduction in syncope from double-blind studies, and an 84% reduction in studies where the control group did not receive a pacemaker.

    “A meta-analysis of all studies suggested a non-significant 17% reduction in syncope from the double-blind studies, and an 84% reduction in the studies where the control group did not receive a pacemaker. 301”

    From 2018 ESC Guidelines for the diagnosis and management of syncope (2018) · cites this paper as [301]

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Authors
Sud, S., Massel, D., Klein, G. J., Leong-Sit, P., Yee, R., Skanes, A. C., Gula, L. J., & Krahn, A. D.
Affiliations
Western University (CA)
Corresponding author
Krahn, Andrew D.
ORCID
Venue
The American Journal of Medicine
Publisher
Elsevier BV
Published
2007-01
Volume
120
Issue
1
Pages
54-62
ISSN
0002-9343 (ISSN-L)
DOI
10.1016/j.amjmed.2006.05.046
OpenAlex
W1987480715
Cited by
151
References
50
Citations by year
2026: 2 · 2024: 2 · 2023: 5 · 2022: 7 · 2021: 8 · 2020: 4 · 2019: 5 · 2018: 6 · 2017: 15 · 2016: 8 · 2015: 9 · 2014: 10 · 2013: 15 · 2012: 15
FWCI
1.57
Type
journal article
Language
en
Open access
closed
Licence
Locations
  • The American Journal of Medicine (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Health Sciences › Medicine › Surgery › Cardiovascular Syncope and Autonomic Disorders
  • Health Sciences › Medicine › Cardiology and Cardiovascular Medicine › Cardiac pacing and defibrillation studies
  • Health Sciences › Medicine › Cardiology and Cardiovascular Medicine › Heart Rate Variability and Autonomic Control
Keywords
vasovagal syncope, permanent pacemaker, cardiac pacing, expectancy effects, blinding, trial heterogeneity, syncope recurrence, cardioinhibitory response, tilt table test, pacing algorithms
MeSH terms
Cardiac Pacing, Artificial, Data Interpretation, Statistical, Female, Humans, Male, Middle Aged, Pacemaker, Artificial, Randomized Controlled Trials as Topic, Syncope, Vasovagal

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